Method and apparatus for removing a carrier part from a carrier with a single operation, and a product removed from a carrier

ABSTRACT

The invention relates to a method for removing from a carrier part with a housing arranged thereon, which carrier part contains openings on the side of the carrier remote from the housing which are filled with encapsulating material, wherein the carrier is engaged on two sides by cutting elements provided with at least one cutting edge, which cutting elements are subsequently moved toward each other such that the carrier, characterized in that before the separation takes place the cutting edge projecting relative to a base of the cutting element is urged into the carrier such that the carrier deforms permanently. The invention also relates to a thus manufactured product and to an apparatus for mechanically performing the method.

[0001] The invention relates to a method according the preamble of claim1. The invention also relates to an apparatus according the preamble ofclaim 7. The invention moreover provides a product removed from acarrier in accordance with the method

[0002] In the production of electronic components, such as for instancesemiconductor chips, the components are usually placed on a carrier, onwhich carrier the components are then encapsulated with for instance asynthetic resin or epoxy, The thus manufactured encapsulated componentsare subsequently released with a part of the carrier from the carrier.

[0003] Such a method and apparatus for cutting semiconductor devices arcdisclosed in the Japanese Patent document JP 06 005758. In this documenta tiebar is cut from a lead frame by a die and a stripper facing eachother. The die and the stripper are provided with protrusions to makecutting grooves in the tiebar, thus reducing the tensile forces to beexerted during the cutting on the tiebar. The reduced tensile forcesexerted on the tiebar protect the packages sealing the semiconductordevices against cracking and/or chipping. This technique is especiallysuited for cutting the leads of conventional leadframes.

[0004] The object of the present invention is to improve the result of aseparating operation of a carrier part that contains openings filledwith encapsulating material, while still performing a single operation,wherein particularly crack formation in a component for processing andburr formation will not or minimal occur or will be less of a problem.

[0005] The invention provides for this purpose a method according claim1. For this purpose the carrier is preferably placed on one side on afirst cutting element provided with a recess and a second cuttingelement having a cutting edge with dimensions which correspond with thedimensions of the recess in the fast cutting element is moved to thefirst cutting clement. In this method the projecting cutting edge of acutting element is preferably urged into the contact side of the carrierwith the cutting element. This single operation, wherein the deformingand the actual separation take place in a single stroke of the cuttingelements, results in a controlled separation process. After applying thesingle-sided or double-sided deformation in the carrier the separationneed be made over a thickness smaller than the thickness of the carrier.In the ideal the e separation Will take place from the position wherethe carrier is most deformed (the deepest par of the imprint) to theother side of the carrier (the deepest part of the imprint on theopposite side or, if there is no second imprint, to the opposite side).Since this path which the separation has to cover is shorter than thethickness of the carrier and because the separation tends to occurconnecting onto a deformation (the source), the position of theseparation can be more readily controlled if the carrier is alreadydeformed prior to: the start of the actual separation process. Thedanger of crack formation and the formation of the“micro-gaps” in theencapsulating material is hereby also eliminated; during the actualseparation a carrier part for separating lies against the cutting edgealong the whole length of the cutting edge despite the often moreelevated openings filled with encapsulating material. The standingcutting edge is urged so far into the carrier that at the position of acutting line both the carrier itself and the encapsulating material inthe openings arranged in the carrier lie against the cutting edge.Cracks in the encapsulating material are thus prevented. It is notedthat the standing cutting edge preferably does not penetrate into theencapsulating material during deforming of the carrier but preciselythat this edge comes to lie against the encapsulating material.

[0006] The single separating operation according to the invention hasthe additional advantage that possible burrs occurring during theseparation do not protrude, or hardly so, relative to the flat sides ofthe carrier. The possible burrs will anyway develop at a distance fromthe flat sides of the carrier; in the most unfavourable case at theposition where the deformation applied by the cutting edge ends. Becausepossible burrs occur at a distance from the flat sides of the carrier,in normal conditions they will not protrude outside the sure defined bythe flat sides of the carrier. These possible burrs do not thereforeform a problem in the further processing of the separated carrier parts.

[0007] The cutting plate engages the carrier on one side, in which plateare arranged recesses of the size of the carrier parts for separating.By means of one or more cutting members (“cutting punches”), likewiseroughly the size of the carrier parts for separating, the carrier partsfor separating are engaged on the side remote from the cutting plate andpressed by the cutting plate. Particularly in the separating ofso-called “leadless packages” also referred to as BLP components (bottomlead packages), the method of separation according the prior art resultsin problems. Since the underside of such carries contains openings whichare also filled with encapsulating material, the cutting plate doers notsupport the carrier part that holds the housing, and also encapsulatingmaterial surfaces facing away from the housing are not supported by thecutting plate. These surfaces formed by encapsulating material are to alimited extent generally more elevated than the underside of thecarrier. As a result the surfaces formed by the encapsulating materialare not properly supported by the cutting plate, whereby crack formationwill occur in the encapsulating material when the separating operationis performed. This is undesirable, Another advantage of the methodaccording the invention is the prevention of burrs on the underside ofthe separated carrier parts. This prevents problems in the furtherprocessing of the separated components. While the problem of burrformation can be solved by reversing the separation process relative tothe carrier, this causes problems in the placing of the cutting plate.There is generally only very little space available adjacently of theencapsulated components for engaging on the carrier, so that the cuttingplate has to have a complex form with contact surfaces of very limitedsize. This reduces the tool life of such a cutting plate and can resultin damage to the carrier material.

[0008] Another advantage of the method according to the invention isthat it is relatively clean. The first deformation of the carriercreates no fragments or other free material portions, or hardly so. Theactual separation path, on which path free material portions will occur,is shortened owing to the at least one deformation, so that here alsoless contamination will occur than in conventional separation. *

[0009] A further advantage of the method according to the invention isthat it is a single operation which is comparatively not verylabour-intensive. Repositioning of the carrier after a first processingstep is also unnecessary. These aspects make the present method reliableand little susceptible to malfunction.

[0010] After performing of the separating operation the cutting elementsare preferably moved apart and the separated carrier part is releasedfrom the cutting elements, wherein one side of the carrier partconnecting onto the separation edge is provided with a deformation. Acarrier part (product) manufactured with the method according to theinvention can thus be easily identified. The separated carrier part alsoforms an independent part of the present invention. Such a carrier partis preferably provided with a deformation on the side of the carrierremote from the housing connecting onto the separation edge.

[0011] The invention also provides an apparatus of the type stated inthe preamble, according claim 7, At least one of the cutting elementsneed be provided with a standing cutting edge. In addition, it can beadvantageous to also modify the control of the cutting elements. Foroptimal results the relative displacement speed of the cutting elementsduring the deformation will generally differ from the relativedisplacement speed of the cutting elements during the separation. Theadvantages as described above can thus be obtained with minimuminvestment.

[0012] Good results are achieved particularly when the projectingcutting edge has a form angled toward the base of the cutting element.Advantageous results are also achieved when the projecting cutting edgecomprises an edge running substantially parallel to a carrier and asloping part connecting thereto and having a form angled toward the baseof the cutting element. For a further improvement in results, theapparatus will generally comprise means for positioning the carrier.

[0013] The present invention will be further elucidated with referenceto the non-limitative embodiments shown in the following figures.Herein:

[0014]FIG. 1 shows a side view of a part of a carrier on which aseparating operation is performed,

[0015]FIGS. 2a and 2 b show side views of cross-sections through a par:of a carrier with housing arranged thereon prior to the performing of aseparation operation according to the prior art,

[0016]FIGS. 2c and 2 d show side views of the cross-sections through thepart of the carrier with housing arranged thereon as shown in FIGS. 2aand 2 b after performing of a separation operation according to theprior art,

[0017]FIG. 3a shows a side view of a cross-section through a part of acarrier with housing arranged thereon before the cutting elements engageon the carrier,

[0018]FIGS. 3b and 3 c show side views of cross-sections through thepart of the carrier with housing arranged thereon as shown in FIG. 3aduring the first part of tie single stroke of the cutting elements,wherein the carrier is deformed by the standing cutting edges,

[0019]FIGS. 3d and 3 e show side views of the cross-sections through thepart of the carrier with the housing arranged thereon as shown in FIGS.3b and 3 c after performing of a separation operation according to thepresent invention,

[0020]FIG. 4a shows a cross-section through a cutting element providedwith a standing cutting edge, and

[0021]FIG. 4b shows a cross-section through an alternative embodimentvariant of a cutting element provided with a standing cutting edge.

[0022]FIG. 1 shows a side view of a cross-section through a carrier 1 onwhich is arranged a housing 2. Carrier 1 is of a composite type andconsists of metal tracks 3, intermediate spaces 4 of which are filledwith epoxy (encapsulating material) during the manufacture of housing 2.The side of carrier 1 remote from housing 2 is not completely flat, andduring feeding of the liquid epoxy is generally covered by a foil layer.A carrier 1 of the shown type is applied inter alia for the productionof so-called leadless packages.

[0023]FIG. 2a shows a cross-section through carrier 1 and housing 2which is perpendicular to the cross-section as shown in FIG. 1. For theseparation of apart of carrier 1 from the remaining part of carrier 1enclosing this part according to the prior art the carrier 1 is placedon a cutting plate 5. In the cross-section shown in this figure only onemetal track 3 of carrier 1 is visible. Metal track 3 supports on cuttingplate. 5. A displaceable knife 6 is situated on the side of the carier 1remote from cutting plate 5. A narrow cutting gap 7 is situated betweencutting plate 5 and knife 6. FIG. 2b shows a cross-section through caner1 and housing 2 parallel to the cross-section shown in FIG. 2a, whereinan epoxy-filled intermediate space 4 of carrier 1 is visible. Clearlyshown is that the epoxy-filled intermediate space 4 of carrier 1 doesnot support on cutting plate 5 but is situated at some distancetherefrom. There is hereby still a limited view of a part of a metaltrack 3.

[0024]FIG. 2c shows a view of carrier 1 and housing 2 as shown in FIG.2a, this time however after performing of the prior art separatingoperation. A drawback of the existing method is that the underside ofthe separated metal track 3 can be provided with a burr 8 protrudingbelow the track 3. Burr 8 makes further processing of the separatedproduct more difficult As shown in FIG. 2d, there is the danger that dueto lack of support by cutting plate 5 the intermediate space 4 filledwith epoxy may begin to display (hairline) cracks 9 during theseparation. Such cracks 9 are undesirable since they can result in areduced lifespan of a separated product, they can make the dimensions ofthe separated product undamageable, and so on.

[0025]FIG. 3a shows a side view of a cross-section through a part of ametal track 3 of a carrier with housing 2 arranged thereon beforecutting element 11,12 engage on metal track 3. The cutting elements areprovided with projecting or standing cutting edges 13,14. After cuttingelements 11,12 have been moved further toward each other, the standingcutting edges engage on metal track 3 such that it deforms permanentlyunder the influence of the exerted pressure. It is noted with emphasisthat the cutting elements do not deform the epoxy arranged inintermediate spaces 4 but are only brought into contact therewith. Seerespectively FIGS. 3b and 3 c above. Cutting element 12 (also referredto as the cutting plate) hereby also comes to lie along the whole lengthof cutting edge 14 against metal carrier 3 respectively the recess 4filled with epoxy. The chance of the problems as illustrated in FIGS. 2cand 2 d is hereby minimized. A possible burr 15 on metal track 3 willthus develop at a distance from a flat side of metal track 3, at whichposition it has no adverse effect (see FIG. 3d for illustration). Thedeformed edge side 16 of metal track 3 can be readily distinguished.FIG. 3e shows a cross-section of the separated carrier part at theposition of a recess filled with epoxy 4. Here also the deformed edgeside 16 of metal track 3 can be distinguished; the recess 4 filled withepoxy is not deformed in angled manner by cutting edge 14.

[0026]FIGS. 4a and 4 b show cutting elements 18,19, of which therespective standing cutting edges 20,21 have alterative forms. Theprojecting cutting edges 20 of cutting element 18 have a form angledtoward the base of cutting element 18. The projecting cutting edges 21of cutting element 19 comprise edges 22 which run substantially parallelto a carrier for processing and which have connecting thereto slopingparts 23 formed at an angle to the base of cutting element 19.

1. Method for removing from a carrier (1) a carrier part with a housing(2) arranged thereon, wherein the carrier (1) is engaged on two sides bycutting elements (5, 6; 11, 12; 18; 19) provided with at least onecutting edge (13, 14; 20, 21), which cutting elements (5, 6; 11, 12; 18;19) are subsequently moved toward each other such that the carrier partis separated from the remaining part of the carrier (1), and before theseparation takes place the cutting edge (13, 14; 20, 21) projectingrelative to a base of the cutting element (5, 6; 11, 12; 18;, 19) isurged into the carrier 1) such that the carrier (1) deforms permanently,characterized in that the carrier part with the housing (2) containsopenings (4) on the side of the carrier (1) remote from the housing (2)which are filled with encapsulating material, and the carrier part withthe housing (2) is removed from the carrier (1) by-punching during whichpunching the carrier part with the housing (2) is supported by a firstcutting element (5, 12, 18, 19) on the side of the carrier (1) remotefrom the housing (2).
 2. Method as claimed in claim 1, characterized inthat the carrier (1) is placed on one side on the first cutting element(5, 12, 18, 19) provided with a recess and a second cutting element (6,11) having a cutting edge (13) with dimensions which correspond with thedimensions of the recess in the first cutting element (5, 12, 18, 19) ismoved to the first cutting element (5, 12, 18, 19).
 3. Method as claimedin claim 1 or 2, characterized in that the projecting cutting edge (13,14; 20, 21) of a cutting element (5, 6; 11, 12; 18; 19) is urged intothe contact side of the carrier (1) with the cutting element (5, 6; 11,12; 18; 19).
 4. Method as claimed in any of the foregoing claims,characterized in that after performing of the separating operation thecutting elements (5, 6; 11, 12; 18; 19) are moved apart and theseparated carrier part is released from the cutting elements (5, 6; 11,12; 18; 19), wherein one side of the carrier part connecting onto theseparation edge is provided with a deformation (16).
 5. Method asclaimed in claim 4, characterized in that the carrier part on the sideof the carrier (1) remote from the housing (2) connecting onto theseparation edge is provided with a deformation (16).
 6. Carrier partwith a housing (2) arranged thereon, manufactured with the method asclaimed in any of the foregoing claims, characterized in that thecarrier part contains openings (4) on the side of the carrier (1) remotefrom the housing (2) which are filled with encapsulating maternal, andone side of the carier part connecting onto the separation edge isprovided with a deformation (16).
 7. Apparatus for removing from acarrier (1) a carrier part with a housing (2) arranged thereon,comprising cutting elements (5, 6; 11, 12; 18; 19) provided with atleast one cutting edge (13, 14; 20, 21) for engaging the carrier (1) ontwo sides, which cutting elements (5, 6; 11, 12; 18; 19) aredisplaceable relative to each other such that the carrier part can beseparated from the remaining part of the carrier (1), and at least oneof the cutting elements (5, 6; 11, 12; 18; 19) comprises a cutting edge(13, 14; 20, 21) projecting relative to a base of the cutting element(5, 6; 11, 12; 18; 19) for applying a permanent deformation (16) in thecarrier (1) on at least one side, characterised in that the apparatuscomprises a first cutting element (5, 12, 18, 19) for supporting thecarrier part with the housing (2) on the side of the carrier (1) remotefrom the housing (2), which carrier part contains openings on the sideof the carrier (1) remote from the housing (2),which are filled withencapsulating material, and a second cutting element (6, 11) cooperatingwith the first cutting element (5, 12, 18, 19) for removing the carrierpart from the carrier (1) by punching.
 8. Apparatus as claimed in claim7, characterized in that the projecting cutting edge (13, 14; 20, 21)has a form angled toward the base of the cutting element (5, 6; 11, 12;18; 19).
 9. Apparatus as claimed in claim 7 or 8, characterized in thatthe projecting cutting edge (13, 14; 20, 21) comprises an edge (22)running substantially parallel to a carrier (1) and a sloping part (23)connecting thereto and having a form at an angle to the base of thecutting element (5, 6; 11, 12; 18; 19).
 10. Apparatus as claimed in anyof the claims 7-9, characterized in that the apparatus also comprisesmeans for positioning the carrier (1).
 11. Apparatus as claimed in anyof the claims 7-10 characterized in that the means for positioning thecarrier (1) are formed by a cutting plate.